Tracer for projectiles.



Patented 0G13. 28, 1913.

(wlmi JOHN BONNER SEMPLE, OF SEWICKLEY, PENNSYLVANIA.

TRACER FOR PROJECTILES.

Application filed November 20, 1912.

To 617/, fle/mm hf may conf-wlw.'

lle it known that l, Jeux l. Slinrnn, residing at Sewicliley, in the county of Allegheuy and State. ot Pennsylvania, a citizen ot the llnited States, have. invented and discovered certain new and useful linprovenients in 'lracers for lrojectiles, of which improvements the following is a specification.

My invention relatesI to ignition devices for tracer chargesl carried in projectiles.

The object ot' nrv invention is a percussion ignition device, operated hy the. explosion ot tho propelling charge, which Ishall be at once, secure against chance. operation, etl'eotive to protect the charge of" tracer nraterial against. a sudden inrush into the chargecontainingchaniher oI the`gases ot explosion when the projectile is tired 'troni a gun, and which shall contain provision against the generation ot a dangerousl degree ot pressure in the chaige-containing chaniber atter tiring` and before. the projectile leaves the niuzzle ofE the gun. 'These and other advantagesl will be appreciated by those practising niy invention.

l have discovered these essential features of a successful tracer-ignition device. First, if the chamber which contains the charge ot tracer inaterial he otherwise open to the gases ot' explosion of the projectile-driving charge, a perfect gas-seal inust be provided in the mouth of that chamber; second, the

ignition deviceI niust certainlyv function at' the proper time, and certainly notI function prematurely; and, third. it the ignition device is operated by the explosion ot the projectile-driving charge, iueaus illust be provided to delay the too rapid burning of the charge while the projectile is Istill in the gun.

In the accompanying drawings, Figure l is a view in longitudinal section of a projectile provided with a chamber for a charge of tracer-n1aterial. a charge therein, and an ignition device. and embodying niy present invention; Fig. 2 is a like view on larger Scale of the stock in which the tracer charge is contained. detached ifroin position in the body of the projectile. (ln inany instances it is preferable, though by no means essential, to provide, such a lstock as a separate and detachable member; out it will be understood that the chamber for the charge of tracer material may be toi-med in the projectile itself.) F35. 3 and -t are views simi- Specification of Letters Patent.

Patented Oct. 28, 1913.

sei-m1 No. 732,543.

lar to Fig. Q, but illustrate various ineditications in detail which may be resorted to. The showing afforded by these supplementary figures is not intended to be exhaustive, and it will be understood that tney serve merely to indicate some permissible \aria tions in structure.

Referring to Figs. l and Q, the projectile l will be seen to be equipped with a tracer, this tracer consisting of a charge of conibustible material a, contained in and located at the anterior end of a chamber 2 which isforined in a stock set in the body of `the projectile. The mouth of this tracer chamber is (but for the presence of the apparatus about to be described) open and cxposed to tht` impacty of the gases of explosion of the, charge which propels the proliectile. This body of combustible material within chamber 2 is provided to burn during the. flight of the projectile, and as it burns to afford means by which the shell may be followed with the eye in its flight.

In the mouth of the chamber 2 are arranged an ignition device, and, cooperating therewith, a. gas seal. The ignition device is of the percussion type, and is caused to opcrate by the pressure of the gases generated on the. explosion of the projedile-propelling charge. Specically, the ignition device consists essentially of a box-like structure, formed of such material and of such proportions as to be rigid and to resist all stresses incident to handling previous to tho firing of the projectile, butcollapsible under the relatively great stress of firing, and by collapsing. exploding a percussio'iL cap propcrly exposed to ignite, the tracer charge itself". ln Figs. l and Q the ignition device consists ot an anvil-member il and a haininer-nieniber el. rl'he anvil-nieniber consists of a block of nietal arranged rearward of the charge ot tracer material within chanv ber 2'; it is provided willi a dished or hollowed-out rear face, with a seatt'or a percussion cap in the center of its posterior dished face, and with a port 5 beneath the percussion-cap seat which gives access for the flash of the exploding cap to the tracer charge, itself. The hainnier-meniber It is a steel disk arranged rear rvard ofi' the anvil ineinber, its periphery resting against the periphery of the dished-out posterior face of the anvil-member; the hammer-member is provided with a pinG centrally arranged ifi on its anterior face, and the disk itself is of such thickness that, while under all ordinary conditions it is rigid, under the enormous pressure of the firing charge it is crushed against the diShed-out face of the anvil-member, and its pin then impinges upon and explodes the percussion cap seated in the anvil-member. The collapsible ignition device is the same in all its parts in Fig. 3. In Fig. -t there are cooperating anvil and hammer members, but, in their functioning, the rear-most of the two members, instead of being distorted and crushed against a hollowed-out face of the member opposed to it, moves forward as a rigid whole to fire thepercussion cap. In this instance there is. provision against forward movement of the rear member, effective under all ordinary conditions, but ineffective to prevent movement under the enormous stress of the firing of the projectile. This proviirsion is found in the collapsible spacing ring Comparing Figs. 2 and el, it will be observed that either the anvil-member or the hammer-member may be the anterior and relatively stationary member, and the other the posterior and movable member.

'Ille gas seal is arranged rearward of the ignition device, and is so disposed and proportioned with relation to the ignition device that, while performing its purpose and effectually protecting the charge of tracer material from ingress of the gases of explosion of the projectile-propelling charge, it will still yield to allow the operating strain to be imparted to the ignition device. It consists preferably (Fig. 2) of a disk or wad 8 of suitable relatively plastic material (preferably le'ad) and of proper thickness, filling the mouth of chamber 2 immediately rearward of the ignition device, and having its edge intimately engaging, by being pressed tightly against the chamber Wall or otherwise; and, of a cupped disk 9 (preferably of copper) arranged rearward of the disk of lead, resting against said -lead disk and flaring` rearwardly. This cupped disk 9 is spun or otherwise forced into the mouth of chamber 2. As shown in Fig. 4 the cupped disk 9 may be omitted, the bore 0f chamber 2 may be ungrooved, and the gas seal may consist merely of a disk or wad 11 of suitable material, preferably lead; the rear face of this disk will preferably be dished. As shown in Fig. 3, the gas seal may take the form 0f a cap lO- of suitable material (preferably copper) spun or otherwisc applied to the rear of the tracer stock, the material being of such nature and the thickness being such as still to permit the ignition device to function. The effectiveness of this form of seal will be in some degree dependent upon the mode of application and the length of margin overlapping the outer surface of the tracer Stock; its peculiar advantage resides in the economy in space which it affords.

In the use of the ignition device which I have described above, I have found it necessary to provide against generation, within the. tracer chamber and after firing and while the projectile is still in the gun, of a pressure so great as to injure or destroy the tracer charge or cause it to explode. The material which forms the tracer charge is, under normal conditions, combustible and slow-burning, but is none the less liable to explosion, or at leastv to sudden and substantially complete destruction, when ig-,

nited under great pressure. Inasmueh as the usefulness of a tracer lies in having the tracer-material burn with relative slowness while the projectile flies, it is necessary to see to it that the tracer material when ignited shall not be subjected to dangerous pressure. When the material is ignited, gases are formed, and if combustion lproceeds in a closed chamber initially filled full of material, the pressure'of c'onlined gases of combustion will soon reach the critical point when Sudden decomposition or explosion will ensue. I have heretofore proposed to guard against sudden decomposition or explosion of the tracer material by providing a body of slow-burning material, forming the posterior part of the charge of the tracer material as a whole which, ignited immediately on the tiring of the gun, will burn so slowly that the tracer material proper will not be ignited under conditions such as to cause its premature destruction, but I -am free to confess that I have not up to this time succeeded in finding and applying a material whose slow-burning nature is such as to make it effective for this purpose without a certain percentage of failure.

My present invention lies in provision against the generation of such a critical pressure as I have alluded to, in the chamber 2, after the ignition device has operated and while the projectile is still in the gun. 'Io this end, my present invention consists in providing in the assembling of the parts a space b rearward of the charge of tracer material a in the chamber 2 and forward of the ignition device proper. This space b may be left empty-z'. e. filled with air at atmospheric prcssure-or (as is indicated in Fig. 3) it may be filled with a combustible material capable of ignition from the percussion cap and of imparting ignition to the body of the tracer charge, and itselfI in its ignition generating no substantial quantity of gas to cause a rise of pressure. Such a material is found in`a mixture of lead oxid. (PbO2) and pure magnesium, which is combustible, and whose products of combustion (MgO and PbO) Aare solids. The presence of such a combustible filler of neutral effect in those particulars under consideration may be advantageous under certain conditions, where the composition of the tracer material may suggest the desirability of such a space-fillingprimer material. In order that I may the more certainly control the rapidity of initial ignition, or eliminate the chances of erratic behavior in functioning, l preferably employ (in case the space /L is left vacant-see l`ig.`2) a shield l2 partially covering the posterior face of the body of tracer' material a within the tracer chamber. Preferably this shield l2 fills the bore of the chamber and is provided with a central perforation. rlhrough this perforation the flash of the exploding ignition cap will have access to the otherwise shielded rear surface of the body a; and thus, while the area of initial ignition is reduced, the extent of initial ignition will be subject to less variation. This perforated shield 12 may be made of cardboard, and in assembling it may be carried to place upon the body of tracer material by a drift bearing a point corresponding in vposition to the lo Aation of the perforation in disk l2; this pointed instrument will insure clearance from the perforation of any barred edge which might otherwise close the perforation wholly or in part. The effect of the pointbearing drift is indicated in the drawing by the shaping of the body of tracer material immediately beneath the perforation in disk 12. l

Comparing Figs. 2 and 3, it will be observed that whereas the bore of chamber 2 is offset to afford a shoulder against which the anvil block 3 may abut in its proper functioning, the bore of the chamber is, in Fig. 3, smooth, and there is no such shoulder for the abutment of the anvil-block, but in this instance the space b is filled With such a neutal material as I have heretofore indicated. In this case the body of neutral material itself is a body against which the anvil-block 3 abats, in order that it may function.V In this particular the structure of Fig. 3 is simpler' than that of Fig. 2, and the use of the neutral filler material is in this respect advantageous.

',lhe ad fantages of my present invention will be clearly understood with a few additional words of explanation. YIt will be appreciated that when the projectile passes from the muzzle of the gun from which it has been tired, the pressure at the rear, which has up to that' point been relatively enormous, and which has imparted to the projectile its speed, is suddenly cut off hand tlm'rea'lter as the projectile flies, the pressure is (relatively speaking) substantially atmospheric pressure or less; and the further fact will be appreciated that, after the projectile `equipped with the tracer leaves the gun, the

pressure generated in the tracer chamber by the ignition then in progress, though utterly inconsi'tlerable in comparison with the enormous pressure of the propelling charge, is sutliciently great to drive from the mouth of the tracer chamber the ignition device and the gas seal together, so that thereafter as the projectile flies, the tracer material will burn freely from its open-mouthed chamber. If the chamber Q were entirely filled with tracer 'material of such character as I ordinarily employ, ignition being ell'ected immediately on firing, there would be danger that, before the projectile. had passed from l' he muzzle ofthe gun, the critical pressure indicated above would have bcen reached within chamber 2; but, by providing the space o, either va ant or filled with a neutral material of the nature indicated, the rate at which pressure will rise within chamber Q in response to the burning of the charge will be very appreciably delayed, and it is a matter of proper proportioning of parts and the size of the charge in view of the nature of the material used, to insure against the generation of the critial pressure before the projectile has passed from the muzzle of the gun. After the pro.- jectile leaves the gun, the danger ceases to exist, as will be understood from the foregoing explanation.

I claim as my invention:

l. A projectile provided with a tracer chamber open-ended to the gases of explosion of the propelling charge, a body of tracer material within said chamber, and a percussion ignition deviceaoperable directly bv the pressure of the propelling gases arrangethin the mouth of the said chamber, a space being left between the body of tracer material within said chamber and the ignition device in the mouth thereof.

2. A projectile provided with a tracer chamber open-ended to the gases of explosion of the propelling charge, a body of tracer material within said chamber, an ignition device arranged in the mouth of thesaid chamber, a space being left between the body of tracer material within said chamber and the ignition device in the mouth thereof, and a shield covering all but a predetermined portion of the posterior face of the body of tracer material within said chamber.

3. A projectile provided with a tracer chamber open-ended to the gases of explosion of the propelling charge, body of tracer material within said chamber, an ignition device arranged in the mouth of' the said chamber, a space being left between the body of tracer material within said chambc' and the ignition device in the mouth thereof, and a body of material combustible without'generation of substantial quant-ities of gas filling 'said space.

4. A. projectile provided with a tracer chamber open-ended to the gases of explosion of the propelling charge, a body of' tracer material within said chamber and occupying the anterior portion thereof, a percussion ignition device operable directly by the pressure of thepropelling gases arranged in the mouth of said chamber, a space interval' being left rearward of the said body o't` -tracer material and between and said ignition device, and a gas seal arranged rearward of lsaid ignition device.

'5. A' projectile provided with a chamber open-ended to the gases of explosion ot the propdlingl charge and containing a charge of tracer material occupying the anterior portion thereof, a perforate anvil-block provided with a (lished posterior face and lspaced at an interval'rearward of the said body of tracer material, a hamn'ler member arranged rearward of said anvil member, and a gas seal arranged rearward of said hannner member and filling the mouth of said tracer chamber.

t'. A projectile provided with a chamber open-ended to the gases of explosion otl lthe propelling charge, a body of tracer material occupying the anterior portion of said tracer chamber, an ignition device arranged within said chamber and .spaced at an interval rearwardly of said body ot tracer material, a disk ot relatively plastic material intimately engaging the bore ot the tracer chamber rearward of aaid ignition device and a second disk of relatively rigid i'naterial arranged rearward of said plastic l disk and filling the mouth ol said tracer chamber. w

7. A projectile provided with a chamber open-ended to the gases of explosion of the propelling charge, a, 'body ot tracer material occupying the anterior portion oi said tracer chamber, an ignition device arranged within said chamber and spaced at an interval rearward of said body of tracer material, a disk/ot relatively plastic material intimately engaging the bore/ otl the tracer chamber rearward o'l` said ignition device, and a .second disk of relatively rigid material arranged rearward of said plastic disk and filling the moutlLofvsaid tracer chamber, and a partial covering over the posterior face of the body of tracer material, limiting the area of ignition.

In testimony whereof I have hereunto set my hand.

JOI IN RUNNER SEM PLE. lV it nesses BAYAan ll. Cnms'rr, Famous J. 'l`o.\r1\ssoN. 

